A sweetened condensed milk which is produced by adding sucrose to a starting milk material such as raw milk, followed by concentrating and sterilizing, retains a distinct flavor of cow's milk. The condensed product is easily used, and is convenient for transport and storage, so that it is widely used in confections such as candies and ice creams. However, recently, the properties which are required for foods have gradually changed, so that more healthy foods are required having equal mouth-feel and flavor, but those tendency to induce tooth decay is prevented. Reflecting such requirements, a boom for so-called healthy confections has also occurred in the confection producing field to commercialize, for example, a candy having reduced tooth decaying property and further to improve such candy.
Usually, a milk material which is used to produce confections such as candy is a sweetened condensed milk or nonfat sweetened condensed milk which is produced by adding tooth-decaying sucrose. When a confection which does not contain the tooth-decaying sucrose is desired to be produced, conventionally, an evaporated milk or a powdered milk which are milk materials not containing sucrose was used. However, when such conventional milk materials are used for production of confections, complication of the production process or loss of quality of products is apt to take place. For example, when non-sugar condensed milk is used for production of candy, i takes a long time to concentrate the candy material solution because of high water content (72.5%), so that problems take place in which the color of the dough after completion becomes excessive and a denaturation of tissue occurs. Moreover, for example, when the powdered milk is used for production of candy, a step for first dissolving the powdered milk in water before preparation is required, so that the resulting products are apt to have surface roughness with passage of time, which may give a problem.
It is explained that the reason why sucrose has tooth decaying property is that sucrose becomes a nutrient for specific bacteria inhabiting the mouth and that the insoluble glucan which is produced by the bacteria facilitates the formation of sordes on teeth. Therefore, if a sugar which does not cause the formation of insoluble glucan is used, a food which has such a property that tooth decay does not readily occur may be provided.
Palatinose is known as one of such a sugar that has reduced tooth decaying property. Palatinose is a disaccharide comprising glucose and fructose bonding by .alpha.-1,6 bond, and has a good sweet taste. Palatinose is produced from sucrose by action of a transferase contained in certain microorganisms by carrying out a cleavage and rebonding reaction of .alpha.-1,6 bond of glucose and fructose in sucrose. Because a reaction mixture after transferase reaction contains various by-products other than palatinose, pure palatinose is produced by microcrystallization after steps of removing salts and concentration or the like. The remaining solution after crystallization is called palatinose syrup, which is a by-product of palatinose production. A typical palatinose syrup has the following composition (Table 1):
TABLE 1 ______________________________________ Composition of palatinose syrup (weight %) ______________________________________ Fructose 16% Glucose 15% Sucrose 4% Palatinose 20% Trehalulose 40% Isomaltose 4% Other sugars 1% Total 100% ______________________________________
This palatinose syrup has a good sweet taste, doesn't have a differing taste, has little color and is considered to have a reduced tooth decaying property. Even if production of a food product is carried out by simply replacing sucrose which is the conventional material for sugar addition by pure palatinose which has a reduced tooth decaying property and a good sweet taste in order to produce a sweetened condensed milk like composition, crystallization of palatinose takes place during production process or storage and it is thus not possible to obtain a sweetened condensed milk composition with a stable quality.